LexicalPreservingPrinter will remove comments when using ASTTransforms.wrapIntoResource

[andrecsilva]

Consider the following snippet:

    String code =
        """
    import java.nio.file.Files;
    import java.io.File;
    import java.io.BufferedWriter;
    class A{
	    void f(File f){
		    // first comment
		    BufferedWriter writer = Files.newBufferedWriter(f.toPath());
		    // second comment
		    System.out.println(1);
		    // third comment
		    System.out.println(2);
	    }
    }
    """;
    ParserConfiguration parserConfiguration = new ParserConfiguration();
    parserConfiguration.setLanguageLevel(ParserConfiguration.LanguageLevel.BLEEDING_EDGE);
    parserConfiguration.setSymbolResolver(new JavaSymbolSolver(new ReflectionTypeSolver()));
    var parser = new JavaParser(parserConfiguration);

    CompilationUnit cu = parser.parse(code).getResult().get();
    LexicalPreservingPrinter.setup(cu);

    var node = cu.findAll(VariableDeclarator.class).get(0);
    var lvd = LocalVariableDeclaration.fromVariableDeclarator(node).get();
    ASTTransforms.wrapIntoResource(lvd.getStatement().asExpressionStmt(), lvd.getVariableDeclarationExpr(), lvd.getScope());

    System.out.println(cu);
    System.out.println("------------------");
    System.out.println(LexicalPreservingPrinter.print(cu));

This will output:

    import java.nio.file.Files;
    import java.io.File;
    import java.io.BufferedWriter;

    class A {

        void f(File f) {
            // first comment
            try (BufferedWriter writer = Files.newBufferedWriter(f.toPath())) {
                // second comment
                System.out.println(1);
                // third comment
                System.out.println(2);
            }
        }
    }

    ------------------
    import java.nio.file.Files;
    import java.io.File;
    import java.io.BufferedWriter;
    class A{
     void f(File f){
  
      try (BufferedWriter writer = Files.newBufferedWriter(f.toPath())) {
          System.out.println(1);
          System.out.println(2);
      }


     }
    }

Notice how the comments disappears if we print it with the LexicalPreservingPrinter, despite being there if we chose not to use it.

This affects all codemods that uses this transform, mainly those using the ResourceLeakFixer transform:
codeql:java/input-resource-leak, codeql:java/output-resource-leak, codeql:java/database-resource-leak, pixee:java/prevent-filewriter-leak-with-nio, pixee:java/resource-leak.

[nahsra]

👀

[andrecsilva]

Can't find a workaround for this, at least one that doesn't involve ditching LexicalPreservingPrinter. I've created an Issue for this in JavaParser's github after narrowing it down a bit more.
javaparser/javaparser#4376